The BESANTEK Corporation BSTHVD9 Personal Safety Voltage Detector, 110V - 22.8kV is a sensor for sensing AC High Voltage. It provides electric engineering personnel, power engineering personnel, firefighting personnel and instrument equipment workers with visual and audible warning when approaching high voltage, so necessary safety precautions can be made. This model can be worn either on the front of a hard hat or on a sleeve using the included elastic cord.